What do you think WB should do about Ezra Miller?

Reboot the universe and junk the DCEU.

Seeing as how the Flash movie is supposedly throwing out Superman anyway, I don't have a problem with this. Even if you want Snyder to come back, he would still have to deal with Miller.

Recast quietly.

I'm pretty sure everyone would understand if they did this. "Oh, look, someone else is playing Flash now. Good, we can move on."

Replace Barry with Wally/someone else.

This would be more tricky given that you would still have to account for what happened to Miller's Barry.

Other.

I don't see Miller getting better without being forced by a court or something. The studio could intervene but even then, it's entirely up to Miller to get help. Having movies coming out doesn't seem to make any difference.